At least 80 people were killed in a shooting at a youth camp on the Norwegian island of Utoya the second of two attacks blamed on a Norwegian suspect authorities have not identified, police said.

Police confirmed that they had arrested a Norwegian man for the attack on a summer youth camp, and that they believed the same man was responsible for the bombing in central Oslo several hours earlier that claimed at least seven lives.

The 80 dead at the camp was a dramatic increase over an earlier police report that at least 10 had died at the youth camp. Police director Oystein Maeland told reporters many more victims were discovered between the two reports, according to The Associated Press.

Anders Behring Breivik, age 32, a self-described nationalist opposed to Islam and to a multi-cultural society.

With the arrest of a lone Norwegian in the twin bomb and shooting attacks today, officials have all but ruled out any connection to international terrorism.

“We have one person in custody and he will be charged in connection with what has happened,” said Justice Minister Knut Storberget during a Friday evening press conference. “We know that he is Norwegian. That is what we know. I don’t think it’s right from my position to go into details about him.”

TV2, Norway’s largest broadcaster, later identified the suspect as Anders Behring Breivik, 32, describing him as a member of “right-wing extremist groups in eastern Norway.” Norwegian police would not confirm the identity of the suspect.

Norway came under deadly attack Friday with a massive bombing in the heart of its power center and a shooting at the ruling party’s youth camp outside the capital.

At least seven people were killed in the blast in Oslo, police said. A number of others were injured both in Oslo and at the youth camp.

It was not immediately clear whether the two incidents were related. But police spokesman Bjorn Erik Sem-Jacobsen told state television broadcaster NRK that authorities have good reason to believe they were.

In northern Utoya Island, a person dressed up as a policeman fired shots at the Labour Party Youth Camp with about 700 people, injuring several people, NRK said. Witnesses described a scene of utter chaos and said many people were shot.

Police have arrested one person in the shooting, NRK said.

Oslo Mayor Fabian Stang said it was a “terrible day” for Norwegians.

An Oslo police spokesman said the explosion was caused by a bomb. No one has claimed responsibility.

Several buildings were badly damaged, many of the windows of the government tower that houses the prime minister’s offices blown out. Emergency teams rushed the injured, some bleeding profusely, to hospitals.